The present invention is directed to an improved disposable leaf gage and bite relationship wafer. The leaf gage and wafer are designed to be easily customized to adapt to the variety of occlusal relationships exhibited by differing patients.
Dentists have used many methods and devices in an attempt to assure the precise location and recording of a patient's mandible. To accurately record the centric relation location of the mandible it is important that both condyles be seated in their most posterior, middle and superior position in the mandibular fossae. The accuracy achieved is highly dependent upon the individual dentist's familiarity with the methodology he choses to use, previous experience, manipulative skills, knowledge of physiology and anatomy, and on the succeeding laboratory procedures. As a result, no single method to assure the precise location and recording of a patient's mandible has become universally accepted. The most popular methods include needlepoint tracing devices; holding the tip of the tongue back in the soft palate; telling the patient to swallow while closing; having the patient pull the lower jaw back or "stick the upper jaw out"; having the patient relax the mandible and let the dentist manipulate it upwards and posteriorly; and, telling the patient to relax and close naturally. More precise but far less popular methods include using clutches and a pantographic recording of mandibular border movements; using an anterior acrylic resin jig (Lucia jig) to guide the lower incisor and mandible in an upward posterior direction; or using a narrow strip of soft metal, popsicle stick, a plastic leaf gage, or firm wax placed anteriorly to exert posterior guidance during closure. Other methods include the use of a functional chew-in, electromyographic recordings, myomoniter, Boos power points or the so called "True Centric" type devices.
Since neuromuscular relaxation is a prerequisite of a physiolgically sound and scientific methodology, ideally all patient's temporomandibular joints should be programmed through a course of wearing a plastic maxillary occlusal splint (bite plane) for a short interval of time or until the mandible has assumed a stable comfortable position prior to making a centric relation jaw registration. This is true whether the necessary dental treatment is an occlusal equilibration, construction of a fixed or removable partial denture, or an entire full mouth occlusal rehabilitation. The dentist determines the extent of occlusal discrepancies in symptom free (temporomandibular joint) patients by testing the existent error using a leaf gage. When a patient bites firmly on a leaf gage which has been inserted between the patient's incisors at the appropriate angle, the patient's condyles are seated in the most superior and comfortable posterior position. However, there are problems associated with the prior art leaf gages. For example, some prior art leaf gages are made of sheets of plastic material affixed at one end with a brad. These plastic leaf gages are not disposable. The plastic leaf gages are sterilized with alcohol and reused by the dentist on different patients. However, the attempts to sterilize the leaf gage between such uses do not effectively provide adequate insurance that any communicable diseases, or diseases such as Acquired Immune Deficiency Syndrome or infectious hepatitis, will not be transmitted from one patient to another. In addition, the prior art leaf gages are not calibrated, so that the dentist cannot easily determine the thickness of the leaf gage used or the distance the patient's mouth has been opened. Most prior art leaf gages are too wide for best anterior tripoding along with the two condyles. Also, if the dentist later determines that another centric relation record is necessary, there is no simple way for the dentist to be sure that the same thickness of leaf gage will again be inserted between the patient's incisors.
It is important that existing occlusal discrepancies be eliminated prior to or along with any relatively extensive restorative dental treatment (crowns, bridges, etc.). This is accomplished by mounting accurate diagnostic dental stone casts on an articulator using a face-bow and performing a verifiable centric relation record to determine the degree and location of the interfering cusps. A diagnostic equilibration is then done on the dental stone teeth casts attached to the dental articulator so that the final result can be analyzed prior to removing any enamel in the mouth. It is not always possible to eliminate centric relation prematurities with an occlusal equilibration; therefore, surgical intervention and/or orthodontic treatment may be necessary. Thus, decision on whether to equilibrate or not and the method for observing, recording and eliminating undesirable tooth interferences is dependent on precise and repeatable closures of the mandible in the centric relation arc.
In addition to the numerous methods for assuring that the patient's mandible is in the most retruded position, many materials and carrying media are advocated for recording and transfering this relationship to an articulator. Dental compound, plaster, zinc oxide-eugenol paste, polysulfide rubber, silicone rubber, polyether rubber, self-activating acrylic resin, dental cement and more than fifty varieties of wax have been used as checkbite materials. These materials are sometimes carried to the mouth with a jig, a metal or plastic frame holding a glass fiber mesh or polyethelene sheet, a fork, a clutch, a soft metal or wax sheet, or these materials are merely applied directly over the teeth or applied to the carrier with a cement spatula. These prior art devices are clumsy and cumbersome to use. Further these devices are bulky and uncomfortable to the patient and frequently provide barriers for accurate closure of the jaw in the terminal hinge position. For example, a prior art plastic frame device and a prior art wire frame device both have a relatively thick posterior edge or end portion curving around the last molars which interferes with the patient's ability to properly close the mouth. Other frames, such as metal frames are both too thick and rigid, contoured incorrectly and consequently, do not accurately record the patient's undesirable tooth interferences.
Therefore, there is a need for an apparatus which is flexible, accurate, inexpensive, disposable, and quickly customized to be adaptable to most patient's occlusal relationships. In addition, there is a further need for an apparatus that can be used as an aid in assuring the accurage mounting of dental casts.